1514794 - Compiling with -fwrapv and --enable-tests breaks in TestWrappingOperations.cpp

Status: RESOLVED WORKSFORME

(Core :: JavaScript Engine, defect)

Description

[Georg Koppen]

Compiling the ESR60 source with `--enable-tests` and specifying -fwrapv results in broken compilation of TestWrappingOperations.cpp:

61:57.58 /var/tmp/build/firefox-2bb5c165697d/mfbt/tests/TestWrappingOperations.cpp:27:1: error: non-constant condition for static assertion
61:57.58  static_assert(WrapToSigned(uint8_t(128)) == -128,
61:57.58  ^~~~~~~~~~~~~
61:57.58 /var/tmp/build/firefox-2bb5c165697d/mfbt/tests/TestWrappingOperations.cpp:27:27:   in constexpr expansion of 'mozilla::WrapToSigned<unsigned char>(128)'
61:57.58 /var/tmp/build/firefox-2bb5c165697d/obj-x86_64-pc-linux-gnu/dist/include/mozilla/WrappingOperations.h:89:59:   in constexpr expansion of 'mozilla::detail::WrapToSignedHelper<UnsignedType>::compute<unsigned char>(((int)aValue))'
61:57.58 /var/tmp/build/firefox-2bb5c165697d/mfbt/tests/TestWrappingOperations.cpp:27:1: error: overflow in constant expression [-fpermissive]
61:57.58 /var/tmp/build/firefox-2bb5c165697d/mfbt/tests/TestWrappingOperations.cpp:27:1: error: overflow in constant expression [-fpermissive]

etc.

This happens with GCC 6.4.0.

Comment 1

[Jason Orendorff [:jorendorff]]

Test case: https://godbolt.org/z/TWWf5M

Bumping to MFBT, but it's unlikely anyone will spend time on this. We don't build with -fwrapv; and it's really a compiler bug. GCC 8.1 fixes it.

Comment 2

[Georg Koppen]

(In reply to Jason Orendorff [:jorendorff] from comment #1)

Test case: https://godbolt.org/z/TWWf5M

Bumping to MFBT, but it's unlikely anyone will spend time on this. We don't
build with -fwrapv; and it's really a compiler bug. GCC 8.1 fixes it.

Fair enough. It's fine closing this as WORKSFORME given that bumping GCC fixes this.